Assembly and Characterization of Biodegradable Polymeric Nanocolloids

The assembly and characterization of the poly(lactide) (PLA)- poly(caprolactone) (PCL) particles described in this work demonstrate the immense potential that biodegradable Janus colloids possess in various fields of application. It is shown that biodegradable polymers of differing chemical structures can self-assemble through nano-precipitation into a colloid that exhibits properties unique to the dual-polymer particles. Hemispherical morphology of the particles is observed and understood through several characterization techniques; further, the morphology is found to be influenced by several parameters, including the material properties of the polymers, the interaction between the PLA and PCL domains, and the interaction between each polymer and the solvent in which they are dispersed. Moreover, high concentrations of PLA-PCL solutions were found to induce morphology that deviates from the hemispherical structure observed at lower concentrations. Stability of PLA homopolymer particles, PCL homopolymer particles, and PLA-PCL particles was investigated at 50¿C and the PCL component was found to confer stability to the PLA-PCL particle at elevated temperatures in aqueous solution

Delayed Enrollment and College Plans: Is There a Postponement Penalty?

Using a representative longitudinal survey of Texas high school seniors who graduated in 2002,we investigate how college postponement is associated with four-year college expectations and attendance—focusing both on the length of delay and the pathway to the postsecondary system. Like prior studies, we show that family background and student academic achievement explains the negative association between delay and college expectations and that these factors, along with two-year college entry pathway, largely accounted for the negative association between postponement and enrollment at a four-year institution in 2006. Although delays of one year or longer are associated with significantly lower odds of attending a baccalaureate-granting institution four years after high school, the longest delays do not incur the most severe enrollment penalties

The Impact of the Texas Top 10 Percent Law on College Enrollment: A Regression Discontinuity Approach

We use regression discontinuity methods on a representative survey of Texas high school seniors to discern the impact on flagship-enrollment behavior of the Texas top 10 percent law, which guarantees admission to any Texas public university to students who graduate in the top decile of their class. By comparing students at and immediately below the cut-point for automatic admission, we find that the top 10 percent law affects flagship enrollment of Hispanic students eligible for the admission guarantee, as well as rank-eligible graduates from high schools where minority students predominate and from high schools with the state average share of economically disadvantaged students. Our findings are robust to various model specifications and different bandwidth choices using local linear estimation

Minority Student Academic Performance Under the Uniform Admission Law: Evidence From The University of Texas at Austin

UT-Austin administrative data between 1990 and 2003 are used to evaluate claims that students granted automatic admission based on top 10% class rank underperform academically relative to lower ranked students who graduate from highly competitive high schools. Compared with white students ranked at or below the third decile, top 10% black and Hispanic enrollees arrive with lower average standardized test scores, yet consistently performed as well or better in grades, first year persistence, and four-year graduation likelihood. A similar story obtains for top 10% graduates from Longhorn high schools verses lower-ranked students who graduated from highly competitive feeder high schools. Multivariate results reveal that high school attended rather than test scores is largely responsible for racial differences in college performance

Test Scores, Class Rank and College Performance: Lessons for Broadening Access and Promoting Success

Using administrative data for five Texas universities that differ in selectivity, this study evaluates the relative influence of two key indicators for college success-high school class rank and standardized tests. Empirical results show that class rank is the superior predictor of college performance and that test score advantages do not insulate lower ranked students from academic underperformance. Using the UT-Austin campus as a test case, we conduct a simulation to evaluate the consequences of capping students admitted automatically using both achievement metrics. We find that using class rank to cap the number of students eligible for automatic admission would have roughly uniform impacts across high schools, but imposing a minimum test score threshold on all students would have highly unequal consequences by greatly reduce the admission eligibility of the highest performing students who attend poor high schools while not jeopardizing admissibility of students who attend affluent high schools. We discuss the implications of the Texas admissions experiment for higher education in Europe

High School Economic Composition and College Persistence

Using a longitudinal sample of Texas high school seniors of 2002 who enrolled in college within the calendar year of high school graduation, we examine variation in college persistence according to the economic composition of their high schools, which serves as a proxy for unmeasured high school attributes that are conductive to postsecondary success. Students who graduated from affluent high schools have the highest persistence rates and those who attended poor high schools have the lowest rates. Multivariate analyses indicate that the advantages in persistence and on-time graduation from four-year colleges enjoyed by graduates of affluent high schools cannot be fully explained by high school college orientation and academic rigor, family background, pre-college academic preparedness or the institutional characteristics. High school college orientation, family background and pre-college academic preparation largely explain why graduates from affluent high schools who first enroll in two-year colleges have higher transfer rates to four-year institutions; however these factors and college characteristics do not explain the lower transfer rates for students from poor high schools. The conclusion discusses the implications of the empirical findings in light of several recent studies that call attention to the policy importance of high schools as a lever to improve persistence and completion rates via better institutional matches

Capitalizing on Segregation, Pretending Neutrality: College Admissions and the Texas Top 10% Law

In response to the judicial ban on the use of race-sensitive admissions, the seventy-fifth Texas legislature passed H.B. 588, which guarantees admission to any Texas public college or university for all seniors graduating in the top decile of their class. We show that high levels of residential and school segregation facilitate minority enrollment at selective public institutions under the uniform admission law because black and Hispanic students who rank at the top of their class disproportionately hail from minority-dominant schools. However, qualifying minority students' lower likelihood of college enrollment at the flagships reflects concentrated disadvantage rather than segregation per se. Copyright 2006, Oxford University Press.